Object detection system and method of detecting object

ABSTRACT

An object detection system is provided with radar detection means ( 2 ), image detection means ( 3 ), and collating means ( 4 ). The collating means ( 4 ) detects a combination of an object detected by the radar detection means ( 2 ) and an object selected among those detected by the image detection means ( 3 ), which is the closest to the object detected by the radar detection means (S 1,  S 2 ), detects a combination of an object detected by the image detection means ( 3 ) and an object selected among those detected by the radar detection means ( 2 ), which is the closest to the object detected by the image detection means (S 3,  S 4 ), and determines when there is a coincidence between the combination of the object detected by the radar detection means ( 2 ) and the selected object as being closest thereto and the combination of the object detected by the image detection means ( 3 ) and the selected object as being closest thereto, that the object detected by the radar detection means ( 2 ) is the same as the object detected by the image detection means (S 5 ).

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to an object detection system and a method ofdetecting an object that detects an object by means of radar and images.

Recently an operation support system, for example, a collision avoidancecontrol system, an adaptive cruise control system, a tracking controlsystem and the like has been increasingly developed. The detection of anobject (obstruction) such as a preceding vehicle is essential for theoperation support system. An object detection system disclosed inpublications JP-A-2003-84064 and JP-A-7-125567 as below includes twodetection units, for example, a radar such as a laser radar, and astereo camera that shoots an image. The object detection system performscollation between the detection results of the radar and the detectedimage. The preceding object is detected based on the aforementionedcollation results.

In the generally employed object detection system, each of two kinds ofdetection units detects an object that is considered as being existent.In other words, the object detection system may occasionally detect aplurality of objects as the preceding object. In this type of objectdetection system, the collation of the detection results is performed inone-way process, that is, the detection result of one detection unit iscollated with respect to the detection result of the other detectionunit so as to identify the object. The collation in the invertedprocess, however, is not performed. This may cause the object detectionsystem to mistakenly identify a plurality of objects. The thusidentified pluralities of objects have to be further subjected to theprocess for narrowing into the single object by performing complicatedoperations. Even if the operation is performed, the identified objectsmay not be narrowed into the single object.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an object detection systemand a method of detecting an object capable of detecting an objectthrough a simple process with high accuracy.

An object detection system according to the invention is provided withradar detection means that detects an object using radar, imagedetection means that detects an object using an image, and collatingmeans that performs collation between a detection result of the radardetection means and a detection result of the image detection means. Thecollating means detects a combination of an object detected by the radardetection means and an object selected among those detected by the imagedetection means, which is the closest to the object detected by theradar detection means, detects a combination of an object detected bythe image detection means and an object selected among those detected bythe radar detection means, which is the closest to the object detectedby the image detection means, determines whether there is a coincidencebetween the combination of the object detected by the radar detectionmeans and the selected object as being closest thereto and thecombination of the object detected by the image detection means and theselected object as being closest thereto, and determines, when there isthe coincidence, that the object detected by the radar detection meansis the same as the object detected by the image detection means.

A method of detecting an object in a system according to the inventionis provided with radar detection means that detects an object using aradar, image detection means that detects an object using an image, andcollating means that performs collation between a detection result ofthe radar detection means and a detection result of the image detectionmeans. The method comprises the steps of detecting a combination of anobject detected by the radar detection means and an object selectedamong those detected by the image detection means, which is the closestto the object detected by the radar detection means, detecting acombination of an object detected by the image detection means and anobject selected among those detected by the radar detection means, whichis the closest to the object detected by the image detection means,determining whether there is a coincidence between the combination ofthe object detected by the radar detection means and the selected objectas being closest thereto and the combination of the object detected bythe image detection means and the selected object as being closestthereto, and determining, when there is the coincidence, that the objectdetected by the radar detection means is the same as the object detectedby the image detection means

In the above-structured object detection system and method, the objectis detected by both the radar detection means and the image detectionmeans. All the detection results of the image detection means arecollated with respect to the respective objects detected by the radardetection means by the collation means. The collation means then selectsthe object among those detected by the image detection means as beingthe closest to the object detected by the radar detection means. Theobject among those detected by the radar detection means is combinedwith the selected object that is the closest thereto. All the detectionresults of the radar detection means are collated with respect to therespective objects detected by the image detection means by thecollation means. The collation means then selects the object among thosedetected by the radar detection means as being the closest to the objectdetected by the image detection means. The object among those detectedby the image detection means is combined with the selected object thatis the closest thereto. It is determined whether there is a coincidencebetween the combination of the object detected by the radar detectionmeans and the selected object as being closest thereto and thecombination of the object detected by the image detection means and theselected object as being closest thereto. When there is the coincidence,it is determined that the object detected by the radar detection meansis the same as the object detected by the image detection means.Accordingly the object included in the coincident combinations is judgedas being the one to be detected by the object detection system. In theobject detection system, the detection results of two kinds of detectionmeans are collated bilaterally so as to select only one object amongthose detected by one detection means collated with respect to theobject detected by the other detection means in the respective collatingprocesses. Further the object that satisfies AND condition between theaforementioned combinations is set as the object to be detected by theobject detection system, resulting in high detection accuracy. In theobject detection system, the object among those detected by onedetection means which is closest to the object detected by the otherdetection means is selected to form the respective combinations. It isthen determined whether there is a coincidence between the combinations.Accordingly the object to be detected by the object detection system maybe easily identified based on detection results of the aforementionedtwo types of detection meanss through the simple process as describedabove while reducing the processing load.

A millimeter-wave radar, laser radar and the like may be used as theradar detection means. A stereo camera may be used as the imagedetection means.

According to the aspect of the invention, the determination whether eachdetection result of the radar detection means and the image detectionmeans indicates the identical object to be detected by the objectdetection system may be made with high accuracy using a simple collatingprocess.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and ether objects, features and advantages of theinvention will become apparent from the following description ofpreferred embodiments with reference to the accompanying drawings,wherein like numerals are used to represent like elements and wherein:

FIG. 1 is a view that shows a structure of an obstruction detectionsystem as an embodiment according to the invention;

FIG. 2 is an explanatory view representing the collating process betweenobjects detected by a radar detection unit as a millimeter-wave radarand objects detected by an image detection unit as a stereo camera,which are provided in an obstruction detection system as shown in FIG.1; and

FIG. 3 is a flowchart representing a collating process executed by theobstruction detection system as shown in FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An embodiment of the object detection system according to the inventionwill be described referring to the drawings.

In this embodiment, the object detection system according to theinvention is applied to an obstruction detection system provided in avehicle so as to detect an obstruction that precedes the vehicle. Theobstruction detection system according to this embodiment is providedwith two detection units, that is, a millimeter-wave radar and a stereocamera

Referring to FIG. 1, an obstruction detection system 1 will bedescribed. FIG. 1 shows a structure of the obstruction detection systemaccording to this embodiment.

The obstruction detection system 1 is provided in a vehicle and detectsan obstruction, that is, a vehicle or the like that precedes thevehicle. The obstruction detection system 1 functions in providingobstruction information to the operation support system such as acollision avoidance control system, an adaptive cruise control system, atracking control system and the like, which requires the informationwith respect to the preceding obstruction. In the obstruction detectionsystem 1, each detection result of two detection units is collatedthrough a simple process such that the obstruction that precedes thevehicle is identified with high accuracy. The obstruction detectionsystem, thus, is provided with a millimeter-wave radar 2, a stereocamera 3, and an ECU 4 (Electronic Control Unit). The obstructiondetection system 1 may be provided independently from the operationsupport system. That is, it may be structured to transmit the detectedobstruction information to the operation support system. Alternativelythe obstruction detection system may be assembled with the operationsupport system.

In this embodiment, the millimeter-wave radar 2 corresponds the radardetection unit, the stereo camera 3 corresponds the image detectionunit, and the ECU 4 corresponds the collating unit.

In this embodiment, a millimetric-wave object refers to an objectdetected by the millimeter-wave radar 2, and an image object refers toan object detected by the stereo camera 3. A fusion object refers to theobject identified as the one that has been detected by themillimeter-wave radar 2 and the stereo camera 3 through collationbetween the millimetric-wave object and the image object. It serves asthe obstruction information supplied by the obstruction detection system1. The independent millimetric-wave object represents the object that isdetected by the millimeter-wave radar 2 only. In other words, theindependent millimetric-wave object is obtained by excluding the fusionobject from the millimetric-wave objects. The independent image objectrepresents the object that is detected by the stereo camera 3 only. Inother words, the independent image object is obtained by excluding thefusion object from the image objects. The respective objects exhibit theinformation with respect to the distance between the vehicle and thepreceding obstruction, the relative speed of the obstruction withrespect to the vehicle, the angle defined by the obstruction and therunning direction of the vehicle (information of the lateral position)for determining the position of the obstruction with respect to thevehicle.

The millimeter-wave radar 2, radar for detecting an object using amillimetric wave, is attached in the center of a front surface of thevehicle. The millimeter-wave radar 2 scans the millimetric wave on thehorizontal plane so as to be emitted from the vehicle forward, andreceives the reflected millimetric wave. The millimeter-wave radar 2measures the time period elapsing from the emission to the receipt ofthe millimetric wave such that the distance from the front end of thevehicle to the preceding object is calculated. The millimeter-wave radar2 further calculates a relative speed of the vehicle with respect tothat of the preceding object using Doppler Effect. The millimeter-waveradar 2 detects the direction of the millimetric wave that reflects mostintensely, based on which an angle defined by the traveling direction ofthe vehicle and that of the preceding object is calculated. Themillimeter-wave radar 2 is capable of detecting the object upon receiptof the reflecting millimetric wave. At every receipt of the reflectingmillimetric wave, therefore, one millimetric object is obtained. Themillimeter-wave radar 2 serves to calculate the distance, the relativespeed, and the angle. However, the ECU 4 may be structured to calculatethose values based on detection results of the millimeter-wave radar 2.

The millimeter-wave radar 2 is capable of detecting the distance and therelative speed with relatively higher accuracy, but detecting the anglewith relatively lower accuracy. As the millimeter-wave radar 2calculates the distance based on the time elapsing from emission of themillimetric wave to reflection thereof, the accuracy in the calculateddistance is relatively higher. As the relative speed is calculated usingDoppler effect, the resultant value of the relative speed exhibits highaccuracy. The millimeter-wave radar 2 fails to identify the point atwhich the millimetric wave reflects most intensely in the widthdirection of the object. As a result, the position in the widthdirection (lateral position) is likely to fluctuate, reducing accuracyin the angle.

The stereo camera 3 includes two sets of CCD cameras (not shown), whichare arranged apart at a distance of approximately several 10 cm in thehorizontal direction. The stereo camera 3 is also attached in the centerof the front surface of the vehicle. The stereo camera 3 transmits therespective image data shot by those two CCD cameras to an imageprocessing portion (not shown). The image processing portion may beassembled with the stereo camera 3 or formed within the ECU 4.

The image processing portion identifies the object based on therespective image data, and obtains the positional information withrespect to the object. The stereo camera 3 is capable of detecting theobject when the object is identified based on two image data. At everyidentification of the object, one image object is obtained. The imageprocessing portion calculates the distance from the front end of thevehicle to the preceding object by triangulation using the difference inviews of the object between two image data. The image processing portioncalculates the relative speed based on the change in the calculateddistance as an elapse of time. The image processing portion detects bothends of the detected object in the width direction such that each angledefined by the traveling direction of the vehicle and the respectiveends of the object is calculated. Accordingly the lateral positionalinformation of the image object includes two types of angle informationwith respect to both ends of the object in the width direction.

Each detection result of the distance and the relative speed of thestereo camera 3 exhibits relatively lower accuracy but the detectionresult of the angle exhibits relatively higher accuracy. As both ends ofthe object in the width direction can be detected with high accuracybased on the left and right image data, the detection result withrespect to the angle may exhibit high accuracy. However, as the imagedata are supplied from left and right CCD cameras apart at several 10cms, the triangulation is performed at substantially acute angle forcalculating the distance. Accordingly, each accuracy of the distance andthe relative speed is reduced

The ECU 4, that is, electronic control unit, includes a CPU (CentralProcessing Unit), a ROM (Read Only Memory), a RAM Random Access Memory),and the like. The ECU 4 is connected with a millimeter-wave radar 2 anda stereo camera 3. The ECU 4 receives the millimetric-wave object fromthe millimeter-wave radar 2, and the image object from the stereo camera3. Then the ECU 4 performs collation between the millimetric-wave objectand the image object so as to obtain obstruction information, forexample, fusion object, independent millimetric-wave object, independentimage object. The ECU 4 receives the image data from the stereo camera3, based on which the image object is obtained.

Referring to FIG. 2, the collating process executed by the ECU 4 will bedescribed. FIG. 2 is a view that represents the process for performingcollation between the millimetric-wave objects and the image objects.The example shown in FIG. 2 indicates five millimetric-wave objects M1to M5 detected by the millimeter-wave radar 2, and six image objects I1to I6 detected by the stereo camera 3.

If the millimetric-wave objects by the number of n_m are detected by themillimeter-wave radar 2, the ECU 4 fetches each of the millimetric-waveobjects one by one. The ECU 4 then collates each of the image objects bythe number of n_i with respect to the fetched millimetric-wave objectsequentially such that the image object closest to the fetchedmillimetric-wave object is selected. In this case, the distance betweenthe vehicle and the object and the angle defined by the vehicle and theobject are collated, and, if required, the relative speed of the objectwith respect to the vehicle may also be collated. In this example, thedifference between the distance from the fetched millimetric-wave objectto the vehicle and the distance from the closest image object to thevehicle is set as a threshold value (several meters) in accordance withthe accuracy of the millimeter-wave radar 2 for the purpose ofperforming the distance collation. If the aforementioned difference inthe distance is equal to or larger than the threshold value, the closestimage object cannot be selected. In this example, the difference betweenthe angle defined by the fetched millimetric object and the travelingdirection of the vehicle and the angle defined by the closest imageobject and the traveling direction of the vehicle is set as a thresholdvalue (several degrees) in accordance with the millimeter-wave radar 2for the purpose of performing the angle collation. If the aforementioneddifference in the angle is equal to or larger than the threshold value,the closest image object cannot be selected. If the closest image objectis selected, the ECU 4 stores a pair of the fetched millimetric-waveobject and the selected image object closest as a millimetric-wave basepair. The ECU 4 repeats the aforementioned collation with respect to themillimetric-wave objects by n_m times.

In the example shown in FIG. 2, when a millimetric-wave object M1 isfetched as the reference, an image object I1 is selected such that amillimetric-wave base pair MP1 is determined. When a millimetric-waveobject M2 is fetched as the reference, an image object I2 is selectedsuch that a millimetric-wave base pair MP2 is determined. When amillimetric-wave object M3 is fetched as the reference, an image objectI2 is selected such that a millimetric-wave base pair MP3 is deterinied.When a millimetric-wave object M4 is fetched as the reference, any oneof the image objects I1 to I6 cannot be selected to form themillimetric-wave base pair because each distance between the respectiveimage objects I1 to I6 and the millimetric-wave object M4 exceeds thethreshold value. When a millimetric-wave object M5 is fetched as thereference, an image object I3 is selected such that a millimetric-wavebase pair MP4 is determined.

If the image objects by the number of n_i are detected by the stereocamera 3, the ECU 4 fetches each of the image objects one by one. TheECU 4 then collates each of millimetric-wave objects by the number ofn_m with respect to the fetched image object sequentially such that themillimetric-wave object closest to the fetched image object is selected.Likewise the collation of the image object with respect to themillimetric-wave object, the distance between the vehicle and theobject, and the angle defined by the vehicle and the object arecollated. In this example, the difference between the distance from thefetched image object to the vehicle and the distance from the closestmillimetric-wave object to the vehicle is set as a threshold value inaccordance with the accuracy of the stereo camera 3. Also the differencebetween the angle defined by the fetched image object and the travelingdirection of the vehicle and the angle defined by the closestmillimetric-wave object and the traveling direction of the vehicle isset as a threshold value in accordance with the accuracy of the stereocamera 3. If the aforementioned difference in the distance or in theangle is equal to or larger than the respective threshold value, theclosest millimetric-wave object cannot be selected. If the closestmillimetric-wave object is selected, the ECU 4 stores a pair of thefetched image object and the selected millimetric-wave object as animage base pair. The ECU 4 repeats the aforementioned collation withrespect to the image objects by n_i times.

In the example shown in FIG. 2, when the image object I1 is fetched asthe reference, the millimetric-wave object M1 is selected such that animage base pair IP1 is determined. When the image object I2 is fetchedas the reference, the millimetric-wave object M2 is selected such thatan image base pair IP2 is determined. When the image object I3 isfetched as the reference, the millimetric-wave object M5 is selectedsuch that an image base pair IP4 is determined. When the image targetobject I4 is fetched as the reference, the millimetric-wave object M5 isselected such that an image base pair IP4 is determined. When the imageobject I5 is fetched as the reference, any one of the millimetric-wavetarget objects M1 to M5 cannot be selected to form the image base pairbecause each difference in the distance between the respectivemillimetric-wave objects M1 to M5 and the image object I5 exceeds thethreshold value. When the image object I6 is fetched as the reference,any one of the millimetric-wave target objects M1 to M5 cannot beselected to form the image base pair because each difference in thedistance between the respective millimetric-wave objects M1 to M5 andthe image object I6 exceeds the threshold value.

The ECU 4 performs comparison between the millimetric-wave base pairsand the image base pairs sequentially so as to select themillimetric-base pair and the image base pair each including theidentical millimetric-wave object and the image object. The ECU 4further sets the selected combination of the millimetric-base pair andthe image base pair each including the identical millimetric-wave objectand the image object as a fusion pair (fusion object). Then theinformation with respect to the distance and the relative speed derivedfrom the millimetric-wave object data, and the information with respectto the angle derived from the image object data is set as the fusionobject information. In the ECU 4, the millimetric-wave objects that havenot been selected as the fusion object is set as independentmillimetric-wave objects, and the image objects that have not beenselected as the fusion object is set as independent image objects,respectively.

In the example shown in FIG. 2, each of the millimetric-wave base pairMP1 and the image base pair FP1 includes the identical millimetric-waveobject M1 and the image object I1, thus forming a fusion pair FP1. Eachof the millimetric-wave base pair MP2 and the image base pair IP2includes the identical millimetric-wave object M2 and the image objectI2, thus forming the fusion pair FP2. Each of the millimetric-wave basepair N4 and the image base pair IP3 includes the identicalmillimetric-wave object M5 and the image object I3, thus forming thefusion pair FP3. The millimetric-wave base pair MP3 has no image basepair including the identical millimetric-wave object and the imageobject. The image base pair IP4 has no millimetric-wave base pairincluding the identical millimetric-wave object and the image object.

The collating process performed in the obstruction detection system 1 asshown in FIG. 1 will be described referring to a flowchart of FIG. 3.The flowchart of FIG. 3 represents the collating process performed bythe obstruction detection system 1 as shown in FIG. 1.

The obstruction detection system 1 detects millimetric-wave objects (n_mobjects) using the millimeter-wave radar 2 for detecting the object, anddetects image objects (n_i objects) using the stereo camera 3 fordetecting the object.

In step S1, in the obstruction detection system 1, each of the n_i imageobjects is collated with each of the millimetric-wave objects fetched asa reference sequentially, and the image object as being closest to thereference millimetric-wave object is selected. In the case where eachdifference in the distance and the angle with respect to themillimetric-wave object and the selected image object is equal to orsmaller than each of the threshold values, the millimetric-wave basepair including the fetched millimetric-wave object and the closest imageobject is determined.

Then in step S2, it is determined whether collation of the n_i imageobjects with respect to the n_m millimetric-wave objects has beencompleted in the obstruction detection system 1. Step S1 is repeatedlyexecuted until completion of the collating process. In this embodiment,each of the detection results of the stereo camera 3 is scanned based onthe detection results of the millimeter-wave radar 2 such that one imageobject that is considered as being closest to the respectivemillimetric-wave objects is identified.

Then in step S3, each of the n_m millimetric-wave objects is collatedwith each of the image objects fetched as a reference sequentially, andthe millimetric-wave object as being closest to the reference imageobject is selected. In the case where each difference in the distanceand the angle with respect to the image object and the selectedmillimetric-wave object is equal to or smaller than each of thethreshold values, the image base pair including the reference imageobject and the closest millimetric-wave object is determined.

The process proceeds to step S4 where it is determined whether collationof the n m millimetric-wave objects with respect to the n_i imageobjects has been completed in the obstruction detection system 1. StepS3 is repeatedly executed until completion of the collating process. Inthis embodiment, each of the detection results of the millimeter-waveradar 2 is scanned based on the detection results of the stereo camera 3such that the millimetric-wave object that is considered as beingclosest to the respective image objects is identified.

In step S5, in the obstruction detection system 1, collation isperformed between all the determined millimetric-wave base pairs and allthe determined image base pairs so as to search a combination of themillimetric-wave base pair and the image base pair each having theidentical millimetric object and the image object. If the aforementionedcombination of the millimetric-wave base pair and the image base pair issearched in the obstruction detection system 1, such combination isdetermined as the fusion pair, and the fusion object informationindicating the distance, relative speed, and the angle is set. In theobstruction detection system 1, two groups of the collation results,that is, the millimetric-wave base pair and the image base pair, derivedfrom the bilateral collations between the millimetric-wave objects andthe image objects are further collated. Only when each of those basepairs includes the identical millimetric-wave object and the imageobject, they are formed into the fusion objects.

In step S6, in the obstruction detection system 1, upon determination ofthe fusion objects (n3 objects), each number of the independentmillimetric-wave objects (n1=n_m−n3) and the independent image objects(n2=n_i−n3) is obtained. In this way, the obstruction detection system 1determines the fusion object, independent millimetric-wave object, andindependent image object at every detection of the millimetric-waveobject and the image object performed by the millimeter-wave radar 2 andthe stereo camera 3, respectively.

In the obstruction detection system 1, bilateral collation between themillimetric-wave objects and the image objects is performed. In the casewhere the two kinds of such collation results coincide with each other,the preceding object is determined as the fusion object. The accuracy(fusion accuracy) in determining the coincidence of the objects detectedby the image and the millimetric wave may be improved to substantially ahigh degree. In the obstruction detection system 1, one of themillimetric-wave object and the image object which is closest to theother object can be selected, and a combination of the millimetric-wavebase pair and the image base pair each including the same objects can besearched through a simple method, thus reducing the processing load.

The obstruction detection system 1 allows collation between thedetection results based on images of the preceding vehicle and thedetection results using the millimetric wave. This may supply theobstruction information with high reliability to various types ofoperation support systems that appropriately support the vehicleoperator to drive the vehicle.

As has been described with respect to the embodiment of the invention,it is to be understood that the invention is not limited to theaforementioned embodiment but may be embodied into various forms.

The embodiment of the invention is applied to the obstruction detectionsystem that is provided in the vehicle. It may be applicable to varioustypes of object detection, for example, contact-free detection.

The embodiment of the invention includes two types of detection units,that is, the millimeter-wave radar and the stereo camera. However, anyother detection unit such as a laser radar may be employed. Furtherthree or more detection units may also be employed.

In the embodiment of the invention, the position of each object isidentified based on the distance, relative speed, and angle. However,other information such as two-dimensional coordinate system may be usedfor identifying the position of the respective objects.

While the invention has been described with reference to exemplaryembodiments thereof, it is to be understood that the invention is notlimited to the exemplary embodiments or constructions. To the contrary,the invention is intended to cover various modifications and equivalentarrangements. In addition, while the various elements of the exemplaryembodiments are shown in various combinations and configurations, whichare exemplary, other combinations and configurations, including more,less or only a single element, are also within the spirit and scope ofthe invention.

1-6. (canceled)
 7. An object detection system comprising: a radardetection unit that detects an object using a radar; an image detectionunit that detects an object using an image; and a collating unit thatperforms collation between a detection result of the radar detectionunit and a detection result of the image detection unit, wherein; thecollating unit detects a combination of an object detected by the radardetection unit and an object selected among those detected by the imagedetection unit A, which is the closest to the object detected by theradar detection unit, detects a combination of an object detected by theimage detection unit and an object selected among those detected by theradar detection unit, which is the closest to the object detected by theimage detection unit, determines whether there is a coincidence betweenthe combination of the object detected by the radar detection unit andthe selected object as being closest thereto and the combination of theobject detected by the image detection unit and the selected object asbeing closest thereto, and determines, when there is the coincidence,that the object detected by the radar detection unit is the same as theobject detected by the image detection unit.
 8. The object detectionsystem according to claim 7, wherein the radar detection unit comprisesat least one of a millimeter-wave radar and a laser radar.
 9. The objectdetection system according to claim 7 or 8, wherein the image detectionunit comprises a stereo camera.
 10. A method of detecting an object in asystem including a radar detection unit that detects an object using aradar, an image detection unit that detects an object using an image,and a collating unit that performs collation between a detection resultof the radar detection unit and a detection result of the imagedetection unit, the method comprising the steps of; detecting acombination of an object detected by the radar detection unit and anobject selected among those detected by the image detection unit, whichis the closest to the object detected by the radar detection unit,detecting a combination of an object detected by the image detectionunit and an object selected among those detected by the radar detectionunit, which is the closest to the object detected by the image detectionunit, determining whether there is a coincidence between the combinationof the object detected by the radar detection unit and the selectedobject as being closest thereto and the combination of the objectdetected by the image detection unit and the selected object as beingclosest thereto, and; determining, when there is the coincidence, thatthe object detected by the radar detection unit is the same as theobject detected by the image detection unit.
 11. The method according toclaim 10, wherein the radar detection unit comprises at least one of amillimeter-wave radar and a laser radar.
 12. The method according toclaim 10 or 11, wherein the image detection unit comprises a stereocamera.